OLIVE-MILL WASTE COMPOST AS A PEAT SUBSTITUTE IN LEAFY VEGETABLES TRANSPLANTS PRODUCTION

Olive-mill waste compost (OMWC) has been added to soil as a fertilizer or used as peat substitute in ornamentals and vegetable transplants production. Therefore, this experiment was carried to evaluate OMWC as a peat substitute in production of broccoli, cabbage, cauliflower, kale, lettuce and endivie transplants. The OMWC was mixed with commercial peat substrate at rates of 0%, 25%, 50% and 75% v/v. Some physical and chemical properties of growing media, as transplant shoot fresh and dry mass, leaf number and leaf area were studied. Water holding capacity decreased and bulk density increased with increasing compost percentage in media. Substrate EC decreased linearly with increasing compost percentage and was lower in growing media after growing period. pH was higher in growing media after transplants growing and was species-dependant. All morphological parameters showed lowest values in treatment when 75% compost was used for all species, but Brassica transplants differ in parameters at other compost percentages. Increasing percentage of OWMC in growing media decreased parameters of lettuce and especially endivie transplants. OMWC could be used as replacement for peat in growing media at a rate of 50% for Brassica and 25% for lettuce and endivie transplants in subirrigated production.